Device-to-device (D2D) communication in the present invention will now be described in brief.
D2D communication refers to communication between an electronic device and another electronic device. In a broad sense, D2D communication means communication between electronic devices or communication between a human-controlled device and a machine. However, D2D communication currently means wireless communication between an electronic device and another electronic device without human interaction.
In the early 1990s when the concept of D2D communication was introduced, D2D communication was regarded simply as remote control or telematics and the market therefor was very limited. However, D2D communication has rapidly grown over the past few years and has developed into a market attracting worldwide attention. Particularly, D2D communication has a great influence on the fields of point of sales (POS), fleet management, remote monitoring of machines and facilities, etc. As D2D communication will serve many more usages in conjunction with legacy mobile communication and wireless ultrahigh-speed Internet or low-power communication solutions such as wireless fidelity (Wi-Fi) and ZigBee, it will be extended to the business-to-consumer (B2C) market beyond the business-to-business (B2B) market.
In the era of D2D communication, all devices equipped with subscriber identity module (SIM) cards are capable of transmitting and receiving data and thus may be managed and controlled remotely. For example, D2D communication may be used in a very large number of devices and equipment such as cars, trucks, trains, containers, vending machines, gas tanks, etc.
Conventionally, terminals are generally managed on an individual basis and thus a one-to-one communication environment is mostly established between a base station (BS) and terminals. When a large number of D2D devices communicate with a BS in this environment, network overload will be caused due to signaling therebetween.
Besides, research has not been actively conducted on specific D2D data transmission schemes in a wireless access system supporting D2D communication and cellular communication.